The present invention relates to a method for isolating and proliferating autologous cancer antigen-specific CD8+ T cells. More particularly, the present invention relates to a method for selecting an epitope recognized by CD8+ T cells from autologous cancer antigens present in blood of individual cancer patients; and isolating autologous cancer antigen-specific CD8+ T cells by using a peptide of the selected epitope, and to a method for mass proliferating CD8+ T cells by using the method.
Since CD8+ T cells have relatively simple functions than other cells such as dendritic cells, CD4+ T cells, and NK cells, it is less likely to cause unexpected side effects during anticancer immunotherapy. Generally, antigen-specific CD8+ T cells are isolated by using MHC class I/peptide multimer, but the method has a drawback in that due to the high cell death rate caused by cell apoptosis after cell isolation, a long period of culture is required to produce a sufficient amount of antigen-specific CD8+ T cells. Accordingly, needed is a surrogate marker which can isolate antigen-specific CD8+ T cells instead of MHC multimer which stimulates a T cell receptor (TCR). Thus, the present inventors have been studying for a long time about the immune regulatory protein, i.e. 4-1BB (CD137).
It has been known that 4-1 BB, which is expressed in T cells activated by an inducible costimulatory molecule, particularly enhances a CD8+ T cell activity and as well as increases expression of anti-apoptotic molecules such as Bcl-2, Bcl-XL, and Bfl-1 so that activation-induced cell death (AICD) is inhibited. The characteristic of 4-1BB simulation are suitable for cancer treatment. Thus, based on the characteristic, a therapeutic effect of an anti-4-1BB mAb on a cancer is validated by using an animal model. In the previous study, the present inventors have established a method for isolating and proliferating antigen-specific CD8 1 T cells by using the anti-4-1BB antibody on the basis of 4-1BB expression of activated CD8+ T cells in an antigen-specific manner (see Korean registered patent No. 10-0882445). However, in vitro and in vivo half life of an antibody are long, and the total result is shown as combination of a signal transduction result through an Fe receptor and a signal transduction effect through a target protein recognized by the antibody. In addition, in many cases, there are various antibodies for the same antigen, and the antibodies show effects having little differences from each other. To overcome this limitation, it has been developed a method for successfully isolating and proliferating antigen-specific CD8+ T cells by using the pentamer, COMP-4-1BBL protein (see Korean registered patent No. 10-1103603).
Those two patents relate to techniques for isolating/mass-culturing CD8 T cells specific for a viral antigen (e.g., EBV/LMP2A, CMV/pp65) which is a heterologous antigen, and the techniques are relatively easy to implement because the in vivo ratio of those cells are high. However, since most of cancer cells are formed by cells which compose our bodies, it is necessary to selectively isolate and mass culture CD8 T cells which recognize an autologous cancer antigen (self-tumor Ag), wherein the autologous cancer antigen is a protein to form the body and overexpressed in cancer cells while present in a low ratio in normal cells.